The present invention relates generally to an in vivo camera system and, in particular, to a system and method for controlling the frame capture rate and frame display rate of images produced by such a camera system.
Several in vivo measurement systems are known in the art. They include swallowable electronic capsules which collect data and which transmit the data to a receiver system. These intestinal capsules, which are moved through the digestive system by the action of peristalsis, are used to measure pH (xe2x80x9cHeidelbergxe2x80x9d capsules), temperature (xe2x80x9cCoreTempxe2x80x9d capsules) and pressure throughout the gastro-intestinal (GI) tract. They have also been used to measure gastric residence time, which is the time it takes for food to pass through the stomach and intestines. These intestinal capsules typically include a measuring system and a transmission system, where a transmitter transmits the measured data at radio frequencies to a receiver system.
Endoscopes are other types of devices that obtain images from the gastro-intestinal tract. There are currently two types of endoscopes. Fiber-optic endoscopes are pushed through the GI tract and use a fiber optic waveguide to transmit a light signal from the area of interest to electronics located outside the patient""s body. Video endoscopes place an electronic camera at the area of interest and transfer the video data through a flexible cable to electronics located externally.
U.S. Pat. No. 5,604,531 assigned to the common assignee of the present application and incorporated herein by reference, teaches an in vivo measurement system, in particular an in vivo camera system, which is carried by a swallowable capsule. In addition to the camera system there is an optical system for imaging an area of the GI tract onto the imager and a transmitter for transmitting the video output of the camera system. The overall system, including a capsule that can pass through the entire digestive tract, operates as an autonomous video endoscope. It images even the difficult to reach areas of the small intestine.
Reference is now made to FIG. 1 which shows a block diagram of the in vivo video camera system described in U.S. Pat. No. 5,604,531. The system captures and transmits images of the GI tract while passing through the gastro-intestinal lumen. The system contains a storage unit 19, a data processor 14, a camera 10, an image transmitter 8, an image receiver 12 (often an antenna array), which usually includes an antenna array, and an image monitor 18. Storage unit 19, data processor 14, image monitor 18, and image receiver 12 are located outside the patient""s body. Camera 10, as it transits the GI tract, is in communication with image transmitter 8 located in capsule 6 and image receiver 12 located outside the body. Data processor 14 transfers frame data to and from storage unit 19 while the former analyzes the data. Processor 14 also transmits the analyzed data to image monitor 18 where a physician views it. The data can be viewed in real time or at some later date.
The number of pictures that need to be taken and which must be analyzed by the attending physician is great. Assuming a minimum of two images per second and a four to five hour dwell time in the GI tract, 30,000 images would be required during the transit of the GI tract by the capsule. If 20 frames per second (fps) are displayed as is standard, the physician would need about 30 minutes to examine the images of the entire GI lumen.
PCT Application PCT/IL98/00608, published as WO 99/30610 and Israeli Application 122602 assigned to the common assignee of the present application and incorporated herein by reference, recite a method for reducing the number of frames captured by an in vivo camera, thereby extending its life. The method discussed in the aforesaid applications requires disconnecting the camera 10 from the power source when motion (velocity) is below a certain threshold value.
It is an object of the present invention to provide a system and method for minimizing the time for reviewing images taken by an in vivo camera system or by endoscopes. This is accomplished by either varying the rate of data display and/ or varying the rate of data acquisition.
In one embodiment of the present invention, an in vivo camera system includes an imager which can have its frame capture rate varied. It also includes at least one sensor for measuring a physical property relatable to the motion of the camera system, a data processor for determining a frame capture rate after receiving data from the sensor and a controller for supplying the determined frame capture rate to the imager The sensor can be, among other things, an accelerometer, an accelerometer connected to an integrator, a pressure sensor, an induction coil, or an ultrasonic transducer.
In another embodiment, an in vivo camera system includes an imager which can have its frame capture rate varied, a storage device for storing frames captured by the imager, an image processor for calculating the required frame capture rate from at least two frames, and a controller for supplying the calculated frame capture rate to the imager.
In yet another embodiment of the present invention, a display system for displaying the output of an in vivo camera system is described. The system includes a frame storage unit for storing frames of the camera system, and an image processor for correlating frames to determine the extent of their similarity. The processor generates a frame display rate which is slower when the frames are generally different and faster when the frames are generally similar. The embodiment also includes a display unit for displaying the frames received from the frame storage unit at the frame display rate. The display system described can also include a controller connected to a frame storage unit and the imager processor. The controller then varies the display rate of the aforementioned display unit. In the above embodiment the at least two frames can be consecutive or non-consecutive frames.
In still another embodiment a video camera system also includes a display system having a frame storage unit for storing at least two frames and an image processor for determining the similarity of at least two frames. The processor generates a frame display rate based on the similarity of the frame. The frame display rate is slower when the frames are generally different and faster when the frames are generally similar. The embodiment also includes a display unit for displaying the frames received from the frame storage at the required frame display rate.
In yet another embodiment an in vivo camera system also includes a display system having a frame storage unit for storing at least two frames. The display system further includes an image processor for correlating at least two frames thereby determining the extent of their similarity and for generating a frame display rate based on that similarity. Finally, the display system includes a display unit for displaying the frames received from the frame storage at the frame display rate.
In one embodiment of the present invention, a method is taught for varying the frame capture rate of a series of frames generated by an in vivo camera system. The in method includes the steps of storing the frames in a storage device, correlating changes in the details of at least two frames, changing the frame capture rate to a predetermined frame capture rate according to the degree of change between the at least two frames and transmitting the capture rate to the imager.
In another embodiment, a method is taught for varying the frame capture rate of a series of frames generated by an in vivo camera system. The method includes the steps of measuring a physical quantity experienced by the camera system, converting the physical quantity to a velocity of the camera, correlating the velocity with a predetermined frame capture rate, and transmitting the predetermined capture rate to the imager. The step of measuring includes the step of measuring acceleration, pressure, induced current or motion, the latter with an ultrasonic transducer.
In yet another embodiment of the present invention, a method is taught for varying the frame display rate of a series of frames generated by an in vivo camera system, the method including the steps of storing the frames in a storage device, correlating changes in the details of at least two frames, and transmitting the required frame display rate to a storage device and a display unit.
Yet a further embodiment of the present invention teaches a method for varying the frame display rate of a series of frames generated by an in vivo camera system which includes the step of repeating the display of a frame a predetermined number of times.
A similar further embodiment teaches a method for varying the frame display rate of a series of frames generated by an in vivo camera system which includes the step of eliminating the display of at least one frame.